'I'm just 22, I can't commit to marriage yet'

My girlfriend and I have been dating for six months now. She wants me to commit to the relationship more, which I find strange because I'm not sure what she means by this. If she wants me to tell her that I will marry her, I can't do that because I have to focus on my career first. I am 22. I don't know what she wants. I don't want to lose her, but I don't think I can commit to this the way she wants me to.
Your girlfriend appears to be in a rush for no apparent reason. And you don't need to be, simply because, as you pointed out, there are other things you need to focus on right now. Tell her how you feel. If she doesn't get it, you won't have a choice but to let her go. If she needs someone who can commit now, ask her what her reasons are. If you are not that person, she needs to know that too.

My boyfriend and I have been together for three years now. Everyone says we are soul mates and we believe it too. And yet, we fight sometimes, for the dumbest reasons. I don't know if this means our relationship is a mistake, because I always assumed soul mates would never fight, no matter what the reason. Should I end this?
I think your idea of soul mates comes from awful Hollywood films starring Julia Roberts. This sort of magical relationship involving two people, who have no disagreements whatsoever and spend their lives hand in hand, sipping cocktails by the beach, is ridiculous. All relationships take work. All of them involve a certain amount of adjustment, which sometimes results in arguments or fights. It's what being human means. We all have likes and dislikes, which means we all run the risk of annoying someone who doesn't have the same likes and dislikes as us. To end your relationship over something like this would be foolish. Communicate with your boyfriend more instead.